Combustor liner replacement panels

ABSTRACT

A replacement panel for repairing a liner for a gas turbine engine combustor, the combustor having a combustion zone formed by inner and outer liners, the replacement panel comprising a sheet of material suitable for use in a combustor liner, at least one opening in the sheet of material, a thermal barrier material applied to the sheet of material adjacent the at least one opening; and a peripheral edge free of thermal barrier material.

BACKGROUND OF THE INVENTION

The technology described herein relates generally to gas turbineengines, and more particularly, to combustor liner replacement panels.

A gas turbine engine includes a compressor for compressing air which ismixed with a fuel and channeled to a combustor wherein the mixture isignited within a combustion chamber for generating hot combustion gases.At least some known combustors include a dome assembly, a cowling, andliners to channel the combustion gases to a turbine, which extractsenergy from the combustion gases for powering the compressor, as well asproducing useful work to propel an aircraft in flight or to power aload, such as an electrical generator. The liners are coupled to thedome assembly with the cowling, and extend downstream from the cowlingto define the combustion chamber.

At least some known liners include a plurality of panels that areconnected together with riveted, bolted, or welded connections. Aportion of the panels include cooling nuggets formed between adjacentpanels that extend radially outwardly from the panels and away from thecombustion chamber. Accordingly, such cooling nuggets are not subjectedto the same degree of heat as portions of the panels adjacent thecombustion chamber, and as such, during operation thermal stresses maybe induced within the panels. Over time, continued operation withthermal stresses may cause panels to thermally fatigue, causingweakening and/or cracking to develop within the panels.

Current repair methods include welding thermal fatigue cracks.Additionally, patches may be attached to areas of panels that areweakened by thermal stresses. However, if the thermal stresses haveinduced thermal fatigue or distress in larger areas of the panels or ina plurality of panels, the combustor may not have enough structuralintegrity within such panels to enable patches to be attached. Thelocation of openings in the panels, such as cooling or dilution holes,and the use of thermal barrier coatings add additional complexity to theuse of welds and patches. In such cases, repair of such panels is not afeasible option, and instead the entire combustor liner is replaced.

Because the liner is coupled to the cowl and the dome assembly, oftenthe entire combustor must be disassembled for the liner to be replaced.Furthermore, when the fasteners are removed from the cowl and domeassembly, precise dimensional relations between the components may bealtered and as a result, special tooling may be required duringre-assembly. Thus, replacing a combustor liner including cooling nuggetsmay be a time-consuming and expensive process.

BRIEF SUMMARY OF THE INVENTION

A replacement panel for repairing a liner for a gas turbine enginecombustor, the combustor having a combustion zone formed by inner andouter liners, the replacement panel comprising a sheet of materialsuitable for use in a combustor liner, at least one opening in the sheetof material, a thermal barrier material applied to the sheet of materialadjacent the at least one opening; and a peripheral edge free of thermalbarrier material.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate several embodiments of thetechnology described herein, wherein:

FIG. 1 is schematic illustration of a gas turbine engine;

FIG. 2 is a partial cross-sectional view of a combustor assembly thatmay be used with the gas turbine engine shown in FIG. 1;

FIG. 3 is an enlarged cross-sectional view of an outer combustor linerused with the combustor shown in FIG. 2;

FIG. 4 is an enlarged cross-sectional view of an alternative version ofan inner combustor liner used with the combustor shown in FIG. 2;

FIG. 5 is an enlarged plan view of the combustor liner shown in FIG. 4;and

FIG. 6 is an enlarged partial cross-sectional view of the combustorliner shown in FIG. 4; and

FIG. 7 is a plan view of a replacement panel.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic illustration of a gas turbine engine 10 includinga low pressure compressor 12, a high pressure compressor 14, and acombustor 16. Engine 10 also includes a high pressure turbine 18 and alow pressure turbine 20. Compressor 12 and turbine 20 are coupled by afirst shaft 22, and compressor 14 and turbine 18 are coupled by a secondshaft 21. In one embodiment, gas turbine engine 10 is a GE90 enginecommercially available from General Electric Aircraft Engines,Cincinnati, Ohio. In another embodiment, gas turbine engine 10 is a CFengine commercially available from General Electric Aircraft Engines,Cincinnati, Ohio.

In operation, air flows through low pressure compressor 12 andcompressed air is supplied from low pressure compressor 12 to highpressure compressor 14. The highly compressed air is delivered tocombustor 16. Airflow from combustor 16 drives turbines 18 and 20 andexits gas turbine engine 10 through a nozzle 24.

FIG. 2 is a partial cross-sectional view of a combustor 30. FIGS. 3 and4 are enlarged views of portions of combustor 30. Combustor 30 may beused with gas turbine engine 10 shown in FIG. 1, and includes a domeassembly 32. A fuel injector (not shown) extends into dome assembly 32and injects atomized fuel through dome assembly 32 into a combustionzone 36 of combustor 30 to form an air-fuel mixture that is igniteddownstream of the fuel injector.

Combustion zone 36 is formed by annular, radially outer and radiallyinner supporting members (not shown) and combustor liners 40. Combustorliners 40 shield the outer and inner supporting members from the heatgenerated within combustion zone 36 and include an inner liner 42 and anouter liner 44. Each liner 42 and 44 is annular and includes amultinugget region 46 and a multihole region 48. Each multinugget region46 extends from dome assembly 32 downstream to each multihole region 48.

Liners 42 and 44 define combustion zone 36. Combustion zone 36 extendsfrom dome assembly 32 downstream to a turbine nozzle (not shown). Outerand inner liners 44 and 42 each include a plurality of panels 50 whichinclude a series of steps 52, each of which form a distinct portion ofcombustor liner 40.

Outer liner 44 and inner liner 42 each include a bolt band 60 and 62,respectively, and a first panel 64 and 66, respectively. Outer bolt band60 and inner bolt band 62 are positioned adjacent to dome assembly 32and extend downstream from dome assembly 32 to first panels 64 and 66,respectively. First panels 64 and 66 are connected downstream from boltbands 60 and 62, respectively. Each adjacent downstream panel 50 isnumbered sequentially, such that second panels 68 and 70 are connecteddownstream from respective first panels 64 and 66. Bolt bands 60 and 62include a plurality of openings 72 sized to receive fasteners 74therethrough. Fasteners 74 secure liners 42 and 44, bolt bands 60 and62, and a cowl assembly 78 to dome assembly 32.

Each combustor panel 50 includes a combustor liner surface 80, anexterior surface 82, and an overhang portion 84. Combustor liner surface80 extends from dome assembly 32 to the turbine nozzle. Combustor linersurface 80 and exterior surface 82 are connected together at overhangportion 84 and form a rear facing edge 86. A plurality of air coolingfeatures 88 separate adjacent combustor panels 50.

Air cooling features 88 include openings 90 which receive airtherethrough from an air plenum (not shown) such that a thin protectiveboundary of air is formed between high temperature combustion gases andcombustor liner surface 80. Furthermore, openings 90 permit convectivecooling of combustor liner 40. Specifically, openings 90 extend throughfeatures 88 which are formed between adjacent panels 50 and radiallyinward from nuggets 92 formed by panels 50. Panels 50 are connectedserially, such that each panel downstream end 100 is connected to anupstream end 102 of an adjacent downstream panel 50. Nuggets 92 areformed between adjacent connected panels respective downstream andupstream ends 100 and 102.

Liner multinugget region 46 includes a plurality of nuggets 92. In theexemplary embodiment, region 46 includes three nuggets 92. Linermultihole region 48 includes a plurality of openings 96 (representativeopenings 96 shown). Other regions of the liner may include multiholetype openings 96, such as depicted in FIGS. 2, 4, and 5.

A layer 110 of thermal barrier material is applied on combustor linersurface 80. Thermal barrier material further insulates combustor linersurface 80 from high temperature combustion gases. In an exemplaryembodiment, thermal barrier coating material is commercially availablefrom Englehart Industries, Wilmington Mass.

During operation, as atomized fuel is injecting into combustion zone 36and ignited, heat is generated within zone 36. Although air enterscombustion zone 36 through cooling features 88 and forms a thinprotective boundary of air along combustor liner surface 80, a variationin exposure of combustor liner surfaces to high temperatures may inducethermal stresses into panels 50. As a result of continued exposure tothermal stresses, over time, panels 50 may become deteriorated.

Deteriorated regions of combustor liner 40 may be removed and replacedusing the methods described herein. More specifically, deterioratedregions of either liner multinugget region 46 and/or liner multiholeregion 48 may be removed and replaced using the methods describedherein.

If a field returned engine, such as engine 10, indicates that combustorliner multinugget region 46 includes at least one deteriorated panel 50,a circumferential cut is made through combustor liner 40 to removedeteriorated panels 50. More specifically, as shown in FIG. 3, the cutis made radially through liner 40 and through a panel body 104, asillustrated with line 120, such that the cut extends from liner exteriorsurface 82 to liner interior surface 80, and such that a portion 122 ofpanel body 104 of panel 50 being cut remains secured within combustor30. Furthermore, the cut is extended through liner 40 downstream fromdeteriorated panels 50 being replaced. Fasteners 74 may be loosened toseparate deteriorated panels 50 from liner 40 for removal.Alternatively, a second cut may then be made upstream from deterioratedpanels 50 being replaced, such that deteriorated panels 50 are separatedand removable from combustor liner 40 to create an opening or missingportion (deficit) in the liner.

Repairs to a combustor liner made as described above may result inreplacement of a complete annular segment of the liner with a comparableor compatible annular liner segment. Accordingly, replacement panels forthis type of combustor liner repair would have the size, shape, andgeometry depicted for the original liners themselves in the accompanyingFigures. Alternatively, repairs may be made with a partial annularsegment or with discrete patches made with replacement panels which areshaped to correspond to a removed segment of the combustor liner, suchas replacement panel 240 depicted in FIGS. 6 and 7.

After deteriorated panels 50 are removed from combustor liners 40,replacement panels may be installed into combustor liners 42 and/or 44.If required, the replacement panels are formed to include a nuggetconfiguration that is substantially identical to that portion of liner40 being replaced. In one embodiment, at least one of a forging, rollwelded ring, or a casting is used as a replacement panel.

Replacement panels may be formed from a planar or substantially planersheet of material which is then formed to the required shape to conformto the deficit in the liner being replaced. This may include forming thesheet of material into a cylindrical, semi-cylindrical, spherical,semi-spherical, or any required shape. Openings are formed into thematerial as required to meet the requirements of the deficit or removedportion of the combustor liner, and may include holes of variouspatterns and sizes. In plan view, the panels may be square, rectangular,or any other shape suitable for use in replacing the applicable deficitin the combustor liner.

The replacement panel is then welded into combustor liner 42 and/or 44,such that the replacement panel is welded to an existing panel 50 thatremains secured within combustor liner 42 and/or 44. More specifically,a downstream side (not shown) of a body of the replacement panel iswelded to panel body portion 122 within combustor 30. In one embodiment,electron beam, EB, welding is used to secure the replacement panelwithin combustor 30. In another embodiment, tungsten inert gas, TIG,welding is used to secure the replacement panel within combustor 30.Thermal barrier coating material may then be applied on the peripheraledge of replacement panel and combustor liner surface 80 in the vicinityof the welding or other securement, and a protective mask may be placedover the openings 96 to maintain their quality checked condition.Fastener 74 is then re-tightened.

If a field returned engine, such as engine 10, indicates that combustorliner multihole region 48 includes at least one deteriorated panel 50, acut is made through combustor liner 40 to remove deteriorated panels 50.More specifically, as shown in FIG. 3, the circumferential cut is maderadially through liner 40 and through a panel body 104, as illustratedwith line 120, such that the cut extends from liner exterior surface 82to liner surface 80, and such that panel body portion 122 remainssecured within combustor 30. Furthermore, the cut is extended throughliner 40 downstream from deteriorated panels 50 being replaced. A secondcut may then be made within multihole region 48 and upstream fromdeteriorated panels 50 being replaced, such that a deteriorated portionof multihole region 48 is separated and removable from combustor liner40 to create an opening or missing portion (deficit) in the liner.Fasteners 74 may then be loosened to separate the deteriorated portionand multinugget region 46 from liner 40 for removal as required.

Repairs to a combustor liner made as described above may result inreplacement of a complete annular segment of the liner with a comparableor compatible annular liner segment. Accordingly, replacement panels forthis type of combustor liner repair would have the size, shape, andgeometry depicted for the original liners themselves in the accompanyingFigures. Alternatively, repairs may be made with a partial annularsegment or with discrete patches made with replacement panels which areshaped to correspond to a removed segment of the combustor liner, suchas replacement panel 240 depicted in FIGS. 6 and 7.

After deteriorated portions of multihole region 48 are removed fromcombustor 30, a replacement panel may be installed into combustor 30. Inone embodiment, at least one of a forging, roll welded ring, a casting,or a sheet metal panel is manufactured and used as a replacement panel.The multihole region openings 96 are pre-formed in the replacement panelbefore the replacement panel is attached. Thermal barrier coating 110 isalso applied as required, including in the vicinity of openings 96 so asto cover edges of the openings 96 and surrounding surfaces of thereplacement panel. In one embodiment, the openings are formed with alaser process. In another embodiment, the openings are formed using anelectron discharge machining, EDM, process. In yet another embodiment,the newly formed openings may be sized differently, reduced, orre-positioned, to facilitate improving cooling of combustor 30.

Replacement panels may be formed from a planar or substantially planersheet of material which is then formed to the required shape to conformto the deficit in the liner being replaced. This may include forming thesheet of material into a cylindrical, semi-cylindrical, spherical,semi-spherical, or any required shape. Openings are formed into thematerial as required to meet the requirements of the deficit or removedportion of the combustor liner, and may include holes of variouspatterns and sizes. In plan view, the panels may be square, rectangular,or any other shape suitable for use in replacing the applicable deficitin the combustor liner.

Replacement panels may be sized and shaped to fit a particular portionremoved from liner 140, or may be pre-fabricated in one or more commonlyused sizes and shapes. Replacement panels may include one or moreopenings 96 extending therethrough and a thermal barrier material 110applied to at least one surface. Thermal barrier material 110 may beapplied to both surfaces, and may be applied so as to cover edges of oneor more openings 96. However, to facilitate securement to the liner 140,replacement panels (referencing replacement panel 240 illustrated inFIGS. 6 and 7) have a peripheral edge 250 which is at least partially,and which may be substantially or fully, free of thermal barriermaterial 110. Replacement panel 240 may also include a beveled orchamfered edge 245 to facilitate welding or other securement processes.

Forming the multihole region openings 96 in the replacement panel andapplying thermal barrier material 110 before installation permits thereplacement panel to be quality checked, including checking andverifying the airflow properties of openings 96, under controlledfactory conditions. The peripheral portion of the replacement panelremains substantially free of thermal barrier material to facilitatesecuring the replacement panel.

The replacement panel is then welded to an existing panel 50 thatremains secured within combustor 30. More specifically, a downstreamside (not shown) of a body of the replacement panel is welded to panelbody portion 122 within combustor 30. In one embodiment, electron beam,EB, welding is used to secure the replacement panel within combustor 30.In another embodiment, tungsten inert gas, TIG, welding is used tosecure the replacement panel within combustor 30. Thermal barriercoating material may then be applied on the peripheral edge ofreplacement panel 240 and combustor liner surface 80 in the vicinity ofthe welding or other securement, and a protective mask may be placedover the openings 96 to maintain their quality checked condition.

Because deteriorated liners are replaced using the method describedherein, combustors 30 are returned to service using a replacementprocess that facilitates improved savings in comparison to removing andreplacing entire combustor liners 40. Furthermore, because thereplacement panels are formed to be substantially identical tooriginally installed panels 50, aerodynamic performance and combustorperformance are not adversely impacted by the replacement panels.

FIG. 4 is an enlarged cross-sectional view of an alternative embodimentof an inner combustor liner 140 that may be used with gas turbine engine10 (shown in FIG. 1). FIG. 5 is an enlarged plan view of combustor liner140. Liner 140 is substantially similar to liners 40 (shown in FIGS. 2and 3), and is installed within a combustor (not shown). The combustorincludes a combustor liner that includes annular inner liner 140 and anannular outer liner (not shown) that is formed substantially similarlyto inner liner 140. Inner liner 140 includes a plurality of panels 150which include a series of steps 152, each of which form a distinctportion of combustor liner 140.

Panels 150 are connected serially. Inner liner 140 includes a bolt band160 and a first panel 164. Inner bolt band 160 is coupled to a domeassembly (not shown) and extends downstream from the dome assembly tofirst panels 164. First panel 164 and panels 150 are connecteddownstream from bolt band 160, such that each adjacent downstream panel150 is numbered sequentially. Accordingly, a second panel 168 isconnected downstream from first panel 164, and a third panel 170 isconnected downstream from second panel 168. Bolt band 160 includes aplurality of openings 172 sized to receive fasteners 74 (shown in FIG.2) for securing liner 140 to the dome assembly.

Each combustor panel 150 includes a combustor liner surface 180, anexterior surface 182, and an overhang portion 184. Combustor linersurface 180 extends from the dome assembly to the turbine nozzle.Combustor liner surface 180 and exterior surface 182 are connectedtogether at overhang portion 184 and form a rear facing edge 186. Aplurality of air cooling features 188 separate adjacent combustor panels150.

Air cooling features 188 include a plurality of openings 190 whichreceive air therethrough from an air plenum (not shown) such that a thinprotective boundary of air is formed between high temperature combustiongases and combustor liner surface 180. Openings 190 are known asdilution openings and extend between liner surface 180 and exteriorsurface 182 to facilitate mixing of combustion gases within thecombustor. In the exemplary embodiment, openings 190 are substantiallycircular. Specifically, each panel 150 includes an upstream end 200, adownstream end 202, and a body 204 extending therebetween. Panels 150are connected, such that each panel downstream end 202 is connected toan upstream end 200 of an adjacent downstream panel 150. Nuggets 192 areformed between adjacent connected panels respective downstream andupstream ends 202 and 200. Nuggets 192 are known as super slot nuggets.In the exemplary embodiment, liner 140 includes six nuggets 192. Regionsof the liner may include multihole type openings 96, such as depicted inFIGS. 4 and 5.

In an alternative embodiment, a layer of thermal barrier material (notshown) is applied on combustor liner surface 180, and enhances thethermal protection of combustor liner surface 180 from high temperaturecombustion gases.

Deteriorated regions of combustor liner 140 may be removed and replacedusing the methods described herein. If a field returned engine, such asengine 10, indicates that combustor liner 140 includes at least onedeteriorated panel 150, a cut is made circumferentially throughcombustor liner 140 to remove deteriorated panels 150. Morespecifically, as shown in FIG. 4, the circumferential cut is maderadially through liner 140 and through a nugget 192, as illustrated withline 220, such that the cut extends from liner exterior surface 182 toliner surface 180. In one embodiment, the cut is made between thirdpanel 170 and a fourth panel 222. Furthermore, the cut is extendedthrough liner 140 downstream from deteriorated panels 50 being replaced.

Repairs to a combustor liner made as described above may result inreplacement of a complete annular segment of the liner with a comparableor compatible annular liner segment. Accordingly, replacement panels forthis type of combustor liner repair would have the size, shape, andgeometry depicted for the original liners themselves in the accompanyingFigures. Alternatively, repairs may be made with a partial annularsegment or with discrete patches made with replacement panels which areshaped to correspond to a removed segment of the combustor liner, suchas replacement panel 240 depicted in FIGS. 6 and 7.

The portion removed from the combustor liner 140 may be partially orfully surrounded by remaining portions of the combustor liner 140.Accordingly, the removed portion may form an aperture in the liner orany other size or shape of deficit in the liner.

After deteriorated portions of liner 140 are removed from the combustor,a replacement panel 240 may be installed into combustor liner 140. Inone embodiment, at least one of a forging, roll welded ring, a casting,or a sheet metal panel is manufactured and used as a replacement panel.

Replacement panels may be formed from a planar or substantially planersheet of material which is then formed to the required shape to conformto the deficit in the liner being replaced. This may include forming thesheet of material into a cylindrical, semi-cylindrical, spherical,semi-spherical, or any required shape. Openings are formed into thematerial as required to meet the requirements of the deficit or removedportion of the combustor liner, and may include holes of variouspatterns and sizes. In plan view, the panels may be square, rectangular,or any other shape suitable for use in replacing the applicable deficitin the combustor liner.

Replacement panel 240 may be sized and shaped to fit a particularportion removed from liner 140, or may be pre-fabricated in one or morecommonly used sizes and shapes. Replacement panel 240 may include one ormore openings 96 extending therethrough and a thermal barrier material210 applied to at least one surface. Thermal barrier material 210 may beapplied to both surfaces, and may be applied so as to cover edges of oneor more openings 96. However, to facilitate securement to the liner 140,replacement panel 240 has a peripheral edge 250 which is at leastpartially, and which may be fully, free of thermal barrier material 110.Replacement panel 240 may also include a beveled or chamfered edge 245to facilitate welding or other securement processes.

Replacement panel 240 may be inspected and tested, such as “flowchecking” openings 190 for specified airflow properties, prior toinstallation because the configuration of openings 190 is not alteredafter installation, such as by application of additional thermal barriermaterial adjacent to or upon edges of one or more openings.

The replacement panel is then welded into combustor liner 140, such thatthe replacement panel is secured within the combustor. Morespecifically, a downstream end (not shown) of the replacement panel iswelded to an existing panel 150 such that a nugget 192 is formed betweenthe replacement panel and panel 150. In one embodiment, electron beam,EB, welding is used to secure the replacement panel within combustorliner 140. In another embodiment, tungsten inert gas, TIG, welding isused to secure the replacement panel within combustor liner 140. Thermalbarrier material may then be applied on remaining panel combustor linersurface 180.

The above-described combustor liner replacement method is cost-effectiveand highly reliable. The method includes the steps of removingdeteriorated panels from the combustor liner, such that deterioratedpanels may be replaced with replacement panels. In one embodiment,deteriorated panels are removed by cutting through the body of thepanel, and replacement panels are then welded to into the combustorliner. As a result, a method is provided which enables deterioratedcombustor liner panels to be removed and replaced in a cost-effectiveand reliable manner.

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

1. A replacement panel for repairing a liner for a gas turbine enginecombustor, the combustor having a combustion zone formed by inner andouter liners, said replacement panel comprising: a sheet of materialsuitable for use in a combustor liner; at least one opening in saidsheet of material; a thermal barrier material applied to said sheet ofmaterial adjacent said at least one opening; and a peripheral edge freeof said thermal barrier material.
 2. A replacement panel in accordancewith claim 1, wherein said replacement panel includes a plurality ofopenings.
 3. A replacement panel in accordance with claim 1, whereinsaid replacement panel comprises a first panel and a second panel joinedby a nugget, said second panel being substantially free of thermalbarrier material.
 4. A replacement panel in accordance with claim 1,wherein said replacement panel further comprises a chamfered edge.
 5. Areplacement panel in accordance with claim 1, wherein said replacementpanel includes a plurality of openings of a plurality of sizes.
 6. Areplacement panel in accordance with claim 1, wherein said replacementpanel is formed as an annular segment.
 7. A replacement panel inaccordance with claim 1, wherein said replacement panel is substantiallyplanar.